1. 17-1 The fossil Record 17-2 Earth’s Early History 17-3 Evolution of Multicellular life 17-4 Patterns of Evolution

2.  Paleontologists are scientists who study Fossils  The fossil record provides evidence about the history of life on Earth.  It also shows how different groups of organisms, including species, have changed over time

3.  More than 99% of all species that have ever lived on Earth have become Extinct, or the species have died out

4.  In Relative Dating, the age of a fossil is determined by comparing its placement with that of fossils in other layers of rock  Scientists also use Index Fossils to compare the relative ages of fossil  To be an index fossil a species must have existed for a short time, but had a large geographic range  Relative dating allows paleontologists to estimate a fossil’s age compared with that of other fossils

5.  Scientists use radioactive decay to assign absolute age to rocks called Radioactive Dating  Radioactive elements decay into nonradioactive elements at a constant rate  A Half-life is the length of time required for half of the radioactive atoms in a sample to decay

6.  Paleontologists use divisions of the Geologic Time Scale to represent evolutionary time  After Precambrian Time, the basic divisions of the geologic time scale are eras and periods

7.  Geologists divide the time between the Precambrian and the present into three Eras  Eras are subdivided into Periods, which range in length from tens of millions of years to less than 2 million years

8.  Pg 422 (1-6)

9.  Earth’s early atmosphere probably contained hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water

10.  Miller and Urey’s experiment suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds present on a primitive Earth

11.  Under certain conditions, large organic molecules can form tiny bubbles called proteinoid microspheres

12.  Microscopic fossils, or Microfossils, of unicellular prokaryotic organisms that resemble modern bacteria have been found in rocks more than 3.5 billion years old

13.  The rise of oxygen in the atmosphere drove some life-forms to extinction, while other life- forms evolve new, more efficient metabolic pathways that used oxygen for respiration

14.  The Endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms

15.  Pg 428 (1-5)

16.  Rich fossil evidence shows that early in the Paleozoic Era, there was a diversity of marine life

17.  During the Devonian, vertebrates began to invade the land  The Mass Extinction at the end of the Paleozoic affected both plants and animals on land and in the seas (95% of all complex life died)

19.  Events during the Mesozoic include the increasing dominance of dinosaurs. The Mesozoic is marked by the appearance of flowering plants

20.  During the Cenozoic, mammals evolved adaptations that allowed them to live in various environments- on land, in water and even in the air

21.  Timeline due at end of class

22.  nor  Six important topics in macroevolution  1) Extinction- 99% of all species

23.  2) Adaptive Radiation is when a small population evolve into diverse forms that live in different ways (Darwins finches)  3) Convergent Evolution is when unrelated organisms come to resemble one another

24.  4) Coevolution is when an organism evolves and is followed by a corresponding change in another organism

25.  5) Punctuated Equilibrium is a pattern of long, stable periods interrupted by brief periods of more rapid change

26.  6) Changes in the expression of developmental genes may explain how these differences evolved  Pg 440 (1-5)